1. Field of the Invention
The present invention relates to a short prevention control apparatus of an air conditioner for an electric vehicle, and, more specifically, to a short prevention control apparatus efficiently detecting a short in a circuit for the air conditioner and adequately breaking a circuit for the air conditioner without affecting the running of the electric vehicle.
2. Description of the Related Art
Technologies relating to detection of a short for electric vehicles, for example, a technology disclosed in Japanese Utility Model Laid Open HEI 6-2901 and a technology disclosed in JP-A-HEI 7-241002, are known.
In the former short detection apparatus for electric vehicles, a short generated between a sink and a battery (a high voltage power source) for the electric vehicle running is detected by detecting a voltage difference caused by a current flowing through a short detecting resistor, and the result of the detection is informed to an electric vehicle driver. In the latter short detection apparatus for electric vehicles, an inverter for driving a motor (for example, alternating current motor) for running the electric vehicle comprises a pair of groups of switching elements. A short in the motor is detected at an input side of the inverter by forcibly controlling one group of switching elements to be on and the other group of switching elements to be off.
When an air conditioner is mounted on such an electric vehicle, usually, a high voltage power source for running of the electric vehicle (for example, a 300 V type high voltage, direct current power source) is used for driving a compressor (a compressor motor) of the air conditioner, and a low voltage power source (for example, a 12 V type low voltage, direct current power source) is used for controlling a driving device for the motor (for example, an inverter).
In electric vehicles, generally, a short detecting circuit is provided in a running control apparatus applied with a high voltage to prevent an electric shock accident due to a short. Usually, such a short detecting circuit may detect a short at any portion of a high voltage circuit.
However, in any type of the above-described known short detection apparatus for electric vehicles, because a short is detected without distinguishing between a running apparatus side and an air conditioner side, even when a short occurs only in the air conditioner, the location cannot be determined. Therefore, when the short is only in the air conditioner, any short prevention also affects the running of the electric vehicle.